No repeat numbers on spinning wheel

Hi - I have a spinning wheel project in Storyline (360) and it is working well with the exception of repeating numbers (1-12 on wheel). Here's the js:

var randomnumber = Math.floor((Math.random(0)*12)+1);
var player = GetPlayer();
player.SetVar('randnum',randomnumber);
console.log(randomnumber);

Any help on how to add something to stop from re-using number would be a big help. Thank you! 

Faye